In this research proposal we will test the hypothesis that reproductive toxicity in the male by polychlorinated aromatic hydrocarbons (PAHs) involves direct effects on testicular cells. SPECIFIC AIM A: To determine in vitro effects of PAHs on Sertoli cells and spermatogenic (germ) cells. The hypothesis is that PAHs cause decreased viability of both Sertoli cells and germ cells. We will conduct these experiments in isolated cultured cells. Cell morphology and functions will be examined. Flow cytometry analysis will be employed. The study will include Sertoli cell cytoskeleton organization and secretory functions which may possibly be altered due to PAHs toxicity. SPECIFIC AIM B: To determine the in vivo effects of PAHs on the cells of the seminiferous epithelium. They hypothesis is that exposure to PAHs will cause disruption of testicular cytoarchitecture yielding decreased number of differentiating germ cells. We will perform light and electron microscopy of testes exposed in vivo to PAHs and will quantify damage using morphometry. Germ cells will be quantified using flow cytometry. SPECIFIC AIM C: To study the effects of humic substances on acute toxicity of PAHs. The hypothesis is that fulvic acid, humic acid, and humin may be used as treatments in PAHs toxicity on isolated Sertoli cells and germ cells. We will do experiments to show that incubation of these cells in medium containing commercially available humic substances prior to the subsequent addition of PAHs block the decreased viability and decreased cell function. SPECIFIC AIM D: To study the possible apoptic mechanisms in PAHs-induced cytotoxicity in Sertoli cells and germ cells. The hypothesis will be tested using DNA electrophoresis and ApopTag labeling of 3'-OH DNA ends. Specific Aim E: To determine that PAHs induced changes in testicular cells alter fucosyltransferase (FT) activity, and Sertoli cells and germ cells are not able to maintain necessary somatic cell-germinal cell adhesion. Bioassays will quantify FT activity and a laser scanning cytometry will measure Sertoli cell-germ cell adhesion. Results from this investigation will provide insight into our understanding of the manner in which PAHs environmental pollutants act to interfere with spermatogenesis.